Anal intercourse is a widely practiced behavior for heterosexual as well as MSM partners. There is substantial epidemiological data on its practice and association with sexually transmitted infections (STI) for men. Substantially less is known about heterosexual anal intercourse practices although it is highly prevalent. We propose to guide development of rectal microbicides by providing descriptive data on anal sex, anal health, and the acceptability of carrier methods for rectal microbicides. Such fundamental information is crucial for understanding rectal microbicide acceptability and use effectiveness. We propose to interview, examine the anorectum, and test for STI's in 896 men and women in Los Angeles and Baltimore. Aim 1 will involve a computer-assisted interview focusing on the behavioral repertoire surrounding PAl, symptoms, and health seeking behaviors. Aim 2 will require a multidisciplinary team to complete assessments involving subject's self-report of behaviors as well as objective criteda of anorectal examination including High Resolution Anoscopy (HRA) image collection of the rectal, anal transition zone, anal canal and perianal areas, and diagnosis of STI's. For Aim 3, eighty subjects who participated in the survey described above and report regular PAl will be recruited for a practical substudy of acceptability of candidate microbicide delivery methods/application techniques. In the acceptability study, subjects will experiment with five different candidate delivery methods/application techniques and report on their use, using water based lubricant as a control. In response to these experiments, changes in the prevalence of anal symptoms, assessed by clinical examination and self-report, will also be measured. Overall goals will include evaluation of correlates between subjects' symptoms and objective signs of rectal STIs and diagnostic findings. Secondly, an investigation of acceptable formulations, based on actual product use will be generated to yield clinically relevant drug development.